Preparation and characterization of Cp-functionalized cycloheptatrienyl- cyclopentadienyl titanium sandwich complexes (troticenes)

Article abstract of DOI:10.1016/j.jorganchem.2011.10.005

Cp-functionalized monotroticenes [(η⁷-C₇H ₇)Ti(η⁵-C₅H₄E)] (2, E = Ph ₂SiCl; 3, E = tBu₂SnCl; 12, E = I) and bitroticenes [(η⁷-C₇H₇)Ti(η⁵-C ₅H₄)]₂E′ (5, E′ = PPh; 6, E′ = BN(SiMe₃)₂; 7, E′ = Cp₂Ti) were prepared by salt elimination metathesis between the monolithiated troticene [(η⁷-C₇H₇)Ti(η⁵-C ₅H₄Li)]·pmdta (1b) (pmdta = N,N′,N′, N″,N″-pentamethyldiethylene-triamine) and the appropriate electrophile. The troticenyl-substituted zirconocene monochloride [(η⁷-C₇H₇)Ti(η⁵-C ₅H₄ZrClCp*₂)] (Cp* = η⁵-C₅Me₅) (8) and hafnocene ethoxide [(η⁷-C₇H₇)Ti{η⁵-C ₅H₄Hf(OEt)Cp₂}] (Cp = η⁵-C ₅H₅) (11), and the heterobimetallic μ-oxo complexes [(η⁷-C₇H₇)Ti(η⁵-C ₅H₄MCp₂)]₂O (9, M = Zr; 10, M = Hf) were obtained instead of the expected zircona- and hafna[1]troticenophanes by reaction of the dilithiated troticene [(η⁷-C₇H ₆Li)Ti(η⁵-C₅H₄Li)]·pmdta (1a) with [Cp₂MCl₂] (M = Zr, Hf) or [Cp* ₂ZrCl₂] in stoichiometric amounts. These compounds were characterized by single crystal X-ray diffraction analyses and, in the case of 2, 3, 5-7, 9, 10 and 12, also by elemental analyses and ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. Exposure of the troticenyl organotin chloride 3 to moisture resulted in its partial hydrolysis and formation of the organostannoxane-bridged bitroticene 4, while palladium-catalyzed Negishi C-C cross-coupling reaction between the troticenylzinc chloride [(η⁷-C₇H₇) Ti(η⁵-C₅H₄ZnCl)] (13) and the iodotroticene 12 or iodobenzene (PhI) led to the fulvalene complexes [(η⁷- C₇H₇)Ti(η⁵-C₅H ₄)]₂ (14) and [(η⁷-C₇H ₇)Ti(η⁵-C₅H₄Ph)] (15). Compound 4 displays an unsymmetrical structure with the troticenyl fragments cis with respect to the Sn-O-Sn core, whereas compound 14 is centrosymmetrically trans oriented.

Full text of DOI:10.1016/j.jorganchem.2011.10.005

Journal of Organometallic Chemistry 696 (2012) 4281e4292
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Preparation and characterization of Cp-functionalized
cycloheptatrienylecyclopentadienyl titanium sandwich complexes (troticenes)
*
Alain C. Tagne Kuate, Swagat K. Mohapatra, Constantin G. Daniliuc, Peter G. Jones, Matthias Tamm
Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
a r t i c l e i n f o
a b s t r a c t
Cp-functionalized monotroticenes [(h h
7-C7H7)Ti(
5-C5H4E)] (2, E ¼ Ph2SiCl; 3, E ¼ tBu2SnCl; 12, E ¼ I) and
Article history:
bitroticenes [(
h
7-C7H7)Ti(h5-C5H4)]2E0 (5, E0 ¼ PPh; 6, E0 ¼ BN(SiMe3)2; 7, E0 ¼ Cp2Ti) were prepared by
Received 19 August 2011
Received in revised form
26 September 2011
salt elimination metathesis between the monolithiated troticene [(h h
7-C7H7)Ti( 5-C5H4Li)]$pmdta (1b)
(pmdta
¼
N,N0,N0,N00,N00-pentamethyldiethylene-triamine) and the appropriate electrophile. The
Accepted 5 October 2011
troticenyl-substituted zirconocene monochloride [(
and hafnocene ethoxide [(
h
7-C7H7)Ti(
h
5-C5H4ZrClCp*2)] (Cp* ¼
h
5-C5Me5) (8)
h
7-C7H7)Ti{
h
5-C5H4Hf(OEt)Cp2}] (Cp ¼
h
5-C5H5) (11), and the heterobimetallic
Keywords:
m
-oxo complexes [(
h
7-C7H7)Ti(
h
5-C5H4MCp2)]2O (9, M ¼ Zr; 10, M ¼ Hf) were obtained instead of the
Sandwich complexes
Cycloheptatrienyl complexes
Cyclopentadienyl ligands
Titanium
expected zircona- and hafna[1]troticenophanes by reaction of the dilithiated troticene [(h -
7-C7H6Li)Ti(h5
C5H4Li)]$pmdta (1a) with [Cp2MCl2] (M ¼ Zr, Hf) or [Cp*2ZrCl2] in stoichiometric amounts. These
compounds were characterized by single crystal X-ray diffraction analyses and, in the case of 2, 3, 5e7, 9,
10 and 12, also by elemental analyses and 1H, 13C and 119Sn NMR spectroscopy. Exposure of the troticenyl
organotin chloride
organostannoxane-bridged bitroticene 4, while palladium-catalyzed Negishi CeC cross-coupling reaction
between the troticenylzinc chloride [(
7-C7H7)Ti( 5-C5H4ZnCl)] (13) and the iodotroticene 12 or iodo-
benzene (PhI) led to the fulvalene complexes [(
7-C7H7)Ti( 5-C5H4)]2 (14) and [( 7-C7H7)Ti( 5-C5H4Ph)]
3 to moisture resulted in its partial hydrolysis and formation of the
h
h
h
h
h
h
(15). Compound 4 displays an unsymmetrical structure with the troticenyl fragments cis with respect to
the SneOeSn core, whereas compound 14 is centrosymmetrically trans oriented.
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
In contrast, the modification of other sandwich complexes is
significantly less well developed and, for instance, mixed cyclo-
heptatrienylecyclopentadienyl (ChteCp) sandwich complexes have
only rarely been employed, even though group 4e6 complexes of
The discovery of bis(
h
5-cyclopentadienyl)iron(II) (ferrocene)
and the elucidation of its sandwich structure by Fischer and Wil-
kinson [1,2] in the 1950s prepared the ground for the development
of modern organometallic chemistry [3]. Today, ferrocene-based
compounds have become an important chemical subclass because
of favorable chemical and physical properties that include high
thermal stability, specific and unique geometries, stability toward
moisture and oxygen and the ability to undergo reversible redox
reactions. Furthermore, the metalation of one or both cyclo-
pentadienyl rings with organolithium reagents followed by the
addition of electrophiles has led to a wider spectrum of function-
alized ferrocenes that have found numerous applications in diverse
areas such as electrochemistry [4], homogeneous catalysis [5],
polymer and medicinal chemistry [6,7], ligand design [8] and
materials science [9].
the type [(
h
7-C7H7)M(
h
5-C5H5)] (M ¼ Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W)
have been known for a long time [10,11]. To date, metalation has only
been achieved for the 3d-transition metal complexes I (Fig. 1), tro-
ticene (M ¼ Ti), trovacene (M ¼ V) and trochrocene (M ¼ Cr), and the
first report on the dilithiation of troticene using nBuLi/tmeda
(tmeda ¼ N,N,N0,N0-tetramethylethylenediamine) dates back to
1974 [12]. Optimization of this method provided access to a number
of difunctionalized troticene derivatives of the type [(
h
7-C7H6E)
Ti(h
5-C5H4E)] (II) [13e15] and, in our hands, to ansa-ChteCp
complexes such as the sila- and germa[1]troticenophanes of type III
(Fig. 1) [16e19]. In a similar fashion, dilithiated trovacene and tro-
chrocene can be obtained, allowing the preparation of related bora-
and sila[1]trovacenophanes [17,20,21], bora-, sila- and germa[1]
trochrocenophanes [21,22,23], dibora- and disila[2]trovaceno-
phanes [20,21] and dibora- and disila[2]trochrocenophanes [24,22].
Recent developments involved the use of nBuLi/pmdta
(pmdta ¼ N,N0,N0,N00,N00-pentamethyldiethylenetriamine), affording
* Corresponding author. Tel.: þ49 0 531 391 5309; fax: þ49 0 531 391 5387.
E-mail address: m.tamm@tu-bs.de (M. Tamm).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.10.005

4282
A.C. Tagne Kuate et al. / Journal of Organometallic Chemistry 696 (2012) 4281e4292
Fig. 2. Mono- and dilithiated cycloheptatrienylecyclopentadienyl titanium complexes.
argon. Ph2SiCl2, tBu2SnCl2, [(h
5-C5H5)2TiCl2], 1,2-diiodoethane,
ZnCl2 and iodobenzene were purchased from SigmaeAldrich Co.
and used as received. Published procedures were used to prepare
Fig. 1. Functionalized cycloheptatrienylecyclopentadienyl sandwich complexes.
[(
pmdta (1b) [25], [(
[(
h h h h
7-C7H6Li)Ti( 5-C5H4Li)]$pmdta (1a), [( 7-C7H7)Ti( 5-C5H4Li)]$
h
5-C5H5)2ZrCl2] [29a], [( 5-C5H5)2HfCl2] [29a],
h
5-C5Me5)2ZrCl2] [29a], Cl2BN(SiMe3)2 [29b,c] and [Pd(dppf)Cl2]
[(h h
7-C7H6Li)Ti( 5-C5H4Li)]$pmdta (1a), which can conveniently be
h
(dppf ¼ 1,10-bis(diphenylphosphanyl)ferrocene) [29d]. NMR spectra
isolated as a dimeric species in crystalline form (Fig. 2) and subse-
quently be employed for the preparation of troticenyldiphosphanes
were recorded on Bruker DPX 200, DRX 400 and AV 300 devices.
such as [(h h
7-C7H6PPh2)Ti( 5-C5H4PPh2)] (dppti) [25] and various
Chemicals shifts (
methylstannane (119Sn), tetramethylsilane (1H, 13C) and 85% H3PO4
31P). Coupling constants (J) are reported in Hertz (Hz) and splitting
d) are reported in ppm and referenced to tetra-
boron-, silicon- and tin-bridged [1]- and [2]troticenophanes [26].
The nBuli/pmdta combination not only proved suitable for the
dilithiation of troticene, but also allowed its selective mono-
lithiation [25]. In agreement with earlier reports, the reaction of
troticene with 1 eq. of nBuLi in diethyl ether initially results in the
(
patterns are indicated as s (singlet), d (doublet), t (triplet) and m
(multiplet). Elemental analyses (C, H, N) were performed by
combustion and gas chromatographic analysis with an Elementar
Vario MICRO elemental analyzer. UV/vis spectra were recorded on
a Shimadzu UV Mini 1240 UV/vis photometer. Electron ionization
mass spectrometry (EI-MS) was performed on a Finnigan MAT 90
device.
kinetically controlled formation of [(h h
7-C7H6Li)Ti( 5-C5H5)], which
can be used for the preparation of Cht-functionalized troticenes
(IV) [15,25,27]. After prolonged reaction times, however, the ther-
modynamically favored Cp-metalated lithiotroticene is formed.
More conveniently, monolithiation with the same regioselectivity
can be achieved in much shorter reaction times by the use of nBuli/
2.2. Synthesis and characterization of [(h h
7-C7H7)Ti( 5-C5H4Si
Ph2Cl)] (2)
pmdta in hexane. The resulting [(h h
7-C7H7)Ti( 5-C5H4Li)]$pmdta
(1b) can be isolated in high yield as a dark green crystalline material
(Fig. 2), which was treated with ClPPh2 to obtain the troticenyl
A solution of Ph2SiCl2 (0.116 g, 0.456 mmol) in hexane (10 mL)
was added dropwise to a suspension of 1b (0.175 g, 0.456 mmol) in
hexane (15 mL) at ꢀ78 ꢁC. The mixture was slowly allowed to reach
ambient temperature, and stirring was continued overnight. The
color of the suspension changed from green to light blue. The solid
was filtered off and washed repeatedly with hexane. Toluene
(10 mL) was added, and the solution was filtered to remove LiCl.
Drying under vacuum afforded 0.150 g (84%) of pure 2 as a blue
solid. Anal. Calcd. (%) for C24H21ClSiTi (420.83): C 68.49; H 5.02.
monophosphane [(h h
7-C7H7)Ti( 5-C5H4PPh2)] [25]. This direct
method for the preparation of troticenes of type V (Fig. 1) is clearly
superior and also more versatile than our previously established
route, which involved the preparation of the halfesandwich
complexes [(
h
5-C5H4PR2)TiCl3] (R ¼ Ph, iPr), followed by reduction
with magnesium in the presence of cycloheptatriene [28].
With the key intermediate 1b in hand, a great variety of func-
tional groups can now be attached selectively at the five-membered
ring, and in this contribution, we wish to report our results on the
exploitation of 1b for the synthesis of a wide range of Cp-
functionalized monotroticenes and bridged bitroticenes. In addi-
tion, several reactions are described in which the use of the dili-
thiotroticene 1a also resulted in the formation of Cp-functionalized
troticenes.
Found: C 67.65; H 5.05. 1H NMR (200 MHz, C6D6, 297 K)
d:
7.67e6.99 (m, 10H, Ph), 5.37 (s, 7H, C7H7), 5.29 (t, JHeH ¼ 5.3 Hz, 2H,
C5H4), 5.11 (t, JHeH ¼ 5.3 Hz, 2H, C5H4). 13C{1H} NMR (50.3 MHz,
C6D6, 297 K) d: 135.5 (s, C6H5), 135.2 (s, i-C6H5), 131.3 (s, C6H5), 128.8
(s, C6H5), 104.5 (C5H4), 102.5 (s, i-C5H4), 101.3 (s, C5H4), 87.8 (s,
C7H7).
2. Experimental section
2.3. Synthesis and characterization of [(
tBu2Cl)] (3) and [(
7-C7H7)Ti( 5-C5H4SntBu2)]2O (4)
h h
7-C7H7)Ti( 5-C5H4Sn-
h
h
2.1. General procedures
A solution of tBu2SnCl2 (0.118 g, 0.390 mmol) in hexane (10 mL)
was added dropwise to a suspension of 1b (0.136 g, 0.355 mmol) in
hexane (12 mL) at ꢀ78 ꢁC. The mixture was allowed to warm up
slowly to ambient temperature, and stirring was continued over-
night, whereby the green suspension turned into a blue-green
solution. After filtration over Celite, the solvent was removed in
vacuo to give a green residue. Recrystallization from pentane
All reactions were performed in a glove box under a dry atmo-
sphere of argon (MBraun 200B) or on a high-vacuum line using
Schlenk techniques. Commercial grade solvents were purified by
use of a solvent purification system from MBraun GmbH and stored
over molecular sieves (4 Å). Tetrahydrofuran was additionally dried
over sodium/benzophenone, distilled, degassed and stored under

A.C. Tagne Kuate et al. / Journal of Organometallic Chemistry 696 (2012) 4281e4292
4283
at ꢀ30 ꢁC gave 0.070 mg (42%) of pure 3 as blue-green crystalline
Calcd. (%) for C34H32Ti3 (584.22): C 69.90; H 5.52. Found: C 68.34; H
6.04. 1H NMR (200 MHz, C6D6, 297 K)
: 5.96 (s, 10H, C5H5), 5.31 (s,
14H, C7H7), 5.0 (t, JHeH ¼ 5.0 Hz, 4H, C5H4), 4.79 (t, JHeH ¼ 5.0 Hz, 4H,
C5H4). 13C{1H} NMR (50.3 MHz, C6D6, 297 K)
: 112.9 (s, C5H5), 110.2
(s, C5H4), 108.0 (s, i-C5H4), 98.3 (s, C5H4), 86.9 (s, C7H7).
solid. Anal. Calcd. (%) for C20H29ClSnTi (471.47): C 50.95; H 6.20.
d
Found: C 51.30; H 6.34. 1H NMR (400 MHz, C6D6, 297 K)
d
: 5.44 (s,
7H, C7H7), 5.21 (t, JHeH ¼ 5.1 Hz, 3JHeSn ¼ 12.8/17.9 Hz, 2H,
a
-C5H4),
d
3
5.11 (t, JHeH ¼ 5.1 Hz, JHeSn ¼ 12.3/17.3 Hz, 2H,
b
-C5H4). 13C{1H}
d: 103.7 (s, i-C5H4), 103.4 (s,
NMR (100.7 MHz, C6D6, 297 K)
2JCeSn ¼ 43.8 Hz,
a
-C5H4), 100.0 (s, 3JCeSn ¼ 40.0 Hz,
b
-C5H4), 87.0 (s,
2.7. Synthesis and characterization of [(h h -
7-C7H7)Ti{ 5-C5H4ZrCl(h5
C5Me5)2}] (8)
C7H7), 36.0 (s, 1JCeSn ¼ 402.3/423.7 Hz, Cq), 30.2 (s, CH3). 119Sn{1H}
NMR d: 30.3.
Compound 4 was obtained as a hydrolyzed by-product of 3
during our attempt to recrystallize the remaining crude product
from hexane by slow evaporation at room temperature. Yield:
11 mg (3.5%). Anal. Calcd. (%) for C40H58OSn2Ti2 (888.04): C 54.10; H
6.58. Found: C 54.61; H 6.23.
A solution of [(h
5-C5Me5)2ZrCl2] (0.177 g, 0.409 mmol) in THF
(15 mL) was added dropwise to a suspension of 1a (0.144 g,
0.372 mmol) in hexane (15 mL) at ꢀ78 ꢁC. The mixture was slowly
allowed to reach ambient temperature, and stirring was continued
overnight. The green suspension turned into a dark brown solution.
After filtration over Celite, the solvent was removed in vacuo to give
a brown residue. The latter was then dissolved in hexane. Slow
evaporation of the solvent afforded a few yellow-green crystals of 8
(0.007 g, 3.1%) suitable for an X-ray diffraction analysis. 1H NMR
2.4. Synthesis and characterization of [(h h
7-C7H7)Ti( 5-C5H4)]2PPh
(5)
A solution of PhPCl2 (0.055 g, 0.248 mmol) in hexane (8 mL) was
added dropwise to a suspension of 1b (0.190 g, 0.495 mmol) in
hexane (20 mL) at ꢀ78 ꢁC. The mixture was allowed to warm up
slowly to ambient temperature, and stirring was continued over-
night. The color of the suspension changed from green to dark
green. The solid was filtered and washed repeatedly with hexane.
Toluene (10 mL) was added and the solution was filtered to remove
LiCl. Drying under vacuum afforded 0.090 g (72%) of pure 5 as
a green solid. Anal. Calcd. (%) for C30H27PTi2 (514.24): C 70.07; H
(200 MHz, THF-d8, 297 K)
2H, C5H4), 4.98 (t, JHeH ¼ 4.0 Hz, 2H, C5H4).
d
: 5.58 (t, JHeH ¼ 4.0 Hz 2H, C5H4), 5.41 (s,
2.8. Synthesis and characterization of [(h h -
7-C7H7)Ti{ 5-C5H4Zr(h5
C5H5)2}]2O (9)
A solution of [(h
5-C5H5)2ZrCl2] (0.249 g, 0.850 mmol) in THF
(20 mL) was added dropwise to a suspension of 1a (0.301 g,
0.773 mmol) in hexane (20 mL) at ꢀ78 ꢁC. The color of the
suspension turned instantaneously from green to light green. The
mixture was allowed to warm up to ꢀ30 ꢁC, and the solid was
isolated by filtration and dried in vacuo. The solid was dissolved in
CH2Cl2 (10 mL) and filtered through Celite to remove LiCl. Evapo-
ration of the solvent gave 0.201 g (30.1%) of pure 9 as a light green
solid. Anal. Calcd. (%) for C44H42OTi2Zr2 (864.99): C 61.10; H 4.89.
5.29. Found: C 69.20; H 5.56. 1H NMR (200 MHz, C6D6, 297 K)
d:
7.50e6.99 (m, 5H, Ph), 5.44 (s, 7H, C7H7), 5.13 (t, JHeH ¼ 5.0 Hz, 2H,
C5H4), 4.98 (t, JHeH ¼ 5.0 Hz, 2H, C5H4). 13C{1H} NMR (50.3 MHz,
1
C6D6, 297 K)
d
: 135.3 (d, JCeP ¼ 23.2 Hz, i-C6H5), 131.8 (d,
3JCeP ¼ 7.0 Hz, m-C6H5), 129.9 (d, 2JCeP ¼ 11.2 Hz, o-C6H5), 126.2 (s,
p-C6H5), 103.2 (d, 1JCeP ¼ 17.0 Hz, i-C5H4), 101.8 (d, 2JCeP ¼ 9.8 Hz,
a-
C5H4), 100.2 (d, 2JCeP ¼ 2.8 Hz,
b
-C5H4), 88.0 (s, C7H7). 31P{1H} NMR
Found: C 60.24; H 5. 10. 1H NMR (200 MHz, CD2Cl2, 297 K)
d: 5.83 (s,
(81 MHz, C6D6, 297 K)
d
: ꢀ29.2 (s).
20H, C5H5), 5.56 (t, JHeH ¼ 4.8 Hz, 4H, C5H4), 5.43 (t, 14H, C7H7). 13
C
{1H} NMR (100.68 MHz, CD2Cl2, 297 K)
d: 147.3 (s, i-C5H4), 111.8 (s,
2.5. Synthesis and characterization of [(
h
7-C7H7)Ti(
h
5-C5H4)]2BN
C5H4), 111.1 (s, C5H5), 101.0 (s, C5H4), 85.5 (s, C7H7).
(SiMe3)2 (6)
2.9. Synthesis and characterization of [(
C5H5)2}]2O (10) and [(
7-C7H7)Ti(
h h -
7-C7H7)Ti{ 5-C5H4Hf(h5
A solution of Cl2BN(SiMe3)2 (0.064 g, 0.265 mmol) in hexane
(5 mL) was added dropwise to a suspension of 1b (0.205 g,
0.534 mmol) in hexane (15 mL) at ꢀ78 ꢁC. The mixture was allowed
to warm up slowly to ambient temperature, and stirring was
continued overnight. The green suspension turned into a green
solution. After filtration over Celite, the solvent was removed in
vacuo to give a green residue. The solid was washed with cold
hexane and dried under vacuum, affording 0.105 g (69%) of pure 6
as a green solid. Anal. Calcd. (%) for C30H40BNSi2Ti2 (577.36): C
62.41; H 6.98. N 2.43 Found: C 61.71; H 6.71; N 2.81 1H NMR
h
h
5-C5H4Hf( 5-C5H5)2OEt)] (11)
h
A solution of [(h
5-C5H5)2HfCl2] (0.140 g, 0.367 mmol) in THF
(15 mL) was added dropwise to a suspension of 1a (0.130 g,
0.334 mmol) in hexane (15 mL) at ꢀ78 ꢁC. The color of the
suspension turned instantaneously from green to light green. The
mixture was allowed to warm up to ꢀ30 ꢁC, and the precipitate was
filtered off and dried in vacuo. This solid was dissolved in toluene
(10 mL) and filtered to remove LiCl. Evaporation of the solvent gave
0.102 g (34.7%) of pure 10 as a light green solid. Anal. Calcd. (%) for
C44H42Hf2OTi2 (1039.52): C 50.84; H 4.07. Found: C 51.28; H 4.34. 1H
(200 MHz, C6D6, 297 K)
d
: 5.51 (s, 14H, C7H7), 5.36 (t, JHeH ¼ 5.3 Hz,
4H, C5H4), 5.14 (t, JHeH ¼ 5.3 Hz, 4H, C5H4). 13C{1H} NMR (50.3 MHz,
NMR (300.13 MHz, THF-d8, 297 K)
C7H7), 5.25 (t, JHeH ¼ 4.7 Hz, 8H, C5H4), 5.10 (t, JHeH ¼ 4.7 Hz, 8H,
C5H4). 13C{1H} NMR (75.4 MHz, THF-d8, 297 K)
: 126.0 (s, i-C5H4),
d: 6.31 (s, 20H, C5H5), 5.41 (s,14H,
C6D6, 297 K) d: 105.3 (s, C5H4), 100.9 (s, i-C5H4), 100.3 (s, C5H4), 87.3
(s, C7H7). 11B{1H} NMR (96.29; Hz, C6D6, 297 K)
d
: 36.7 (bs).
d
112.6 (s, C5H4), 109.1 (s, C5H5), 98.0 (s, C5H4), 85.9 (s, C7H7).
After separation of the light green solid, the filtrate was evap-
orated in vacuo to give a brown residue. Attempts to recrystallize
this brown residue by slow evaporation of its diethyl ether solution
afforded a small quantity of 11 as green crystals suitable for an X-
ray diffraction analysis.
2.6. Synthesis and characterization of [(
C5H5)2 (7)
h
7-C7H7)Ti( 5-C5H4)]2Ti(h5
h
-
A solution of [(h
5-C5H5)2TiCl2] (0.060 g, 0.260 mmol) in hexane
(10 mL) was added dropwise to a suspension of 1b (0.200 g,
0.520 mmol) in hexane (20 mL) at ꢀ78 ꢁC. The mixture was slowly
allowed to reach ambient temperature, and stirring was continued
overnight. After removing the solvent, the residue was extracted
with toluene, followed by evaporation of the solvent. The resulting
purple solid was washed with hexane and dried under vacuum
affording 0.085 g (56%) of pure 7 as a dark purple powder. Anal.
2.10. Synthesis and characterization of [(h h
7-C7H7)Ti( 5-C5H4I)] (12)
A solution of 1,2-diiodoethane (0.40 g, 1.40 mmol) in hexane
(20 mL) was added dropwise to a suspension of 1b (0.450 g,
1.170 mmol) in hexane (10 mL) at ꢀ78 ꢁC. The reaction mixture was

4284
A.C. Tagne Kuate et al. / Journal of Organometallic Chemistry 696 (2012) 4281e4292
slowly warmed up to room temperature, and stirring was
continued overnight. The color of the suspension turned from dark
green to green. The solid was isolated by filtration, washed several
times with hexane until the solution became colorless and dried in
vacuo. The solid was then dissolved in toluene (15 mL) and filtered
through Celite to remove LiCl. Repeated crystallization from
toluene at ꢀ30 ꢁC gave 0.216 g (56%) of pure 12 as a green crys-
talline solid. Anal. Calcd. (%) for C12H11ITi (329.99): C 43.68; H 3.36.
2.13. Synthesis and characterization of [(h h
7-C7H7)Ti( 5-C5H4Ph)]
(15)
A mixture of iodobenzene (0.085 g, 0.414 mmol), 13 (0.090 g,
0.296 mmol) and [Pd(dppf)Cl2] (5 mol%) in THF (18 mL) was heated
at 60 ꢁC for 16 h. After evaporation of the solvent, the residue was
extracted with cold toluene and filtered through glass wool. Drying
the filtrate under vacuum afforded a light green solid. Recrystalli-
zation from toluene at ꢀ30 ꢁC gave 0.038 mg (46%) of pure 15 as
a green crystalline solid. Anal. Calcd. (%) for C18H16Ti (280.19): C
77.16; H 5.75. Found: C 76.05; H 5.89. 1H NMR (200 MHz, C6D6,
Found: C 43.06; H 3.74. 1H NMR (200 MHz, C6D6, 297 K)
d: 5.46 (s,
7H, C7H7), 5.03 (t, JHeH ¼ 5.8 Hz, 2H, C5H4), 4.68 (t, JHeH ¼ 5.8 Hz,
2H, C5H4). 13C{1H} NMR (50.3 MHz, C6D6, 297 K)
99.7 (s, C5H4), 89.1 (s, C7H7).
d: 105.5 (s, C5H5),
297 K)
d
: 7.29e7.00 (m, 5H, C5H4), 5.38 (t, JHeH ¼ 5.8 Hz, 2H, C5H4),
5.34 (s, 7H, C7H7), 4.98 (t, JHeH ¼ 5.8 Hz, 2H, C5H4). 13C{1H} NMR
(50.3 MHz, C6D6, 297 K) d: 143.5 (s, i-C6H5), 129.2 (s, C6H5), 127.1 (s,
2.11. Synthesis of [(h h
7-C7H7)Ti( 5-C5H4ZnCl)] (13)
C6H5), 125.5 (s, C6H5), 98.6 (s, C5H5), 95.8 (s, C5H4), 88.5 (s, C7H7),
88.3 (s, i-C5H4). MS (EI, 70 eV): m/z 280 (Mþ). HR-MS (EI; m/z):
Calcd for C18H16Ti (Mþ), 278.07728; found, 278.07693.
A solution of ZnCl2 (0.214 g, 1.57 mmol) in THF (12 mL) was
added dropwise to a suspension of 1b (0.548 g, 1.43 mmol) in
hexane (10 mL) at ꢀ78 ꢁC. The reaction mixture was slowly warmed
up to room temperature, and stirring was continued for 2 h. The
color of the suspension turned from dark green to light green. The
solid was filtered off and washed thoroughly with hexane. Drying in
vacuo afforded 0.326 g (75%) of a light green powder. This was used
directly for the next reaction without further purification and
characterization.
2.14. Single-crystal X-ray structure determinations
Numerical details are summarized in Tables 1 and 2. Crystals
were mounted in inert oil on glass fibers. Intensity measurements
were performed at low temperature on Oxford Diffraction diffrac-
tometers using monochromated Mo Ka or mirror-focussed Cu Ka
radiation. Absorption corrections were based on multi-scans.
Structures were refined anisotropically on F2 using the program
SHELXL-97 [30]. In several cases, the ring H atoms were refined
freely or with distance restraints (see supplementary crystallo-
graphic data for details); other hydrogen atoms were included
using idealized rigid methyl groups or a riding model. Exceptions
and special features: Compounds 2 and 15 crystallize by chance in
Sohncke space groups. Compound 8 displays a difference peak of
3.2 e Åꢀ3 close to the Ti atom. For compound 9.THF, the THF was
badly disordered and could not be refined satisfactorily; the
program SQUEEZE [31] was therefore used to remove mathemati-
cally the effects of the solvent. The ethyl group of compound 11 is
disordered. Several C atoms of compound 15 displayed irregular
displacement ellipsoids, which were therefore constrained to be
more regular using the program commands DELU and ISOR.
2.12. Synthesis and characterization of [(h h
7-C7H7)Ti( 5-C5H4)]2 (14)
A mixture of 12 (0.140 g, 0.435 mmol), 13 (0.165 g, 0.544 mmol)
and [Pd(dppf)Cl2] (5 mol%) in THF (15 mL) was heated at 60 ꢁC for
16 h. The solution was then concentrated to half of its volume,
filtered and kept at ꢀ30 ꢁC for 2 h. A green precipitate of 14 was
isolated by filtration, washed with diethyl ether and dried in vacuo,
yield: 0.045 g (25.5%). Anal. Calcd. (%) for C24H22Ti2 (406.17): C
70.97; H 5.46. Found: C 64.90; H 5.15. 1H NMR (200 MHz, C6D6,
297 K)
d
: 5.34 (s,14H, C7H7), 5.02 (t, JHeH ¼ 5.8 Hz, 4H, C5H4), 4.87 (t,
JHeH ¼ 5.8 Hz, 4H, C5H4). 13C{1H} NMR (50.3 MHz, C6D6, 297 K)
d:
113.0 (s, i-C5H5), 96.8 (s, C5H4), 94.2 (s, C5H4), 87.8 (s, C7H7). MS (EI,
70 eV): m/z 406 (Mþ). HR-MS (EI; m/z): Calcd for C24H22Ti2 (Mþ),
406.06808; found, 406.06827. UV/vis (toluene): lmax
(
3 ) ¼ 686 (30).
Table 1
Crystal and structure refinement data for 2e8.
2
3
4
5
6
7
8
Empirical formula
C24H21ClSiTi
8.1585(2)
8.6708(2)
28.1704(6)
90
C20H29ClSnTi
17.8885(4)
8.1679(2)
14.3083(2)
90
101.086(2)
90
2051.60(7)
4
C40H58OSn2Ti2
10.3880(6)
13.0499(6)
15.5167(6)
101.228(4)
94.871(4)
107.948(4)
1939.00(16)
2
C30H27PTi2
10.3366(2)
9.6075(2)
23.9270(2)
90
94.814(2)
90
2367.78(7)
4
C30H40BNSi2Ti2
19.3186(6)
10.0599(2)
15.2774(6)
90
105.198(4)
90
2865.22(15)
4
C34H32Ti3
39.2431(14)
17.2466(8)
7.6738(2)
90
90
90
5193.7(3)
8
C32H41ClTiZr
10.3369(2)
14.9335(2)
17.9112(2)
90
99.783(2)
90
2724.68(7)
4
a (Å)
b (Å)
c (Å)
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
90
90
V (Å3)
1992.79(8)
4
Z
Formula weight
Space group
T (K)
420.85
P212121
100(2)
1.54184
1.403
471.47
P21/c
100(2)
1.54184
1.526
14.146
34,535
888.04
P1
100(2)
1.54184
1.521
514.29
P21/n
100(2)
1.54184
1.443
577.42
C2/c
100(2)
0.17073
1.339
584.30
Fdd2
100(2)
0.71073
1.494
600.22
P21/c
100(2)
1.54184
1.463
l
(Å)
Dcalcd (g cm-3
(mmꢀ1
Reflection collected
)
m
)
5.476
26,266
13.712
30,906
6.486
31,214
0.661
58,056
0.923
41,908
6.657
38,792
Independent reflections 4071 Rint ¼ 0.0376 4245 Rint ¼ 0.0379 7979 Rint ¼ 0.0208 4890 Rint ¼ 0.0247 3847 Rint ¼ 0.0605 3088 Rint ¼ 0.0691 5660 Rint ¼ 0.0270
Goodness of fit on F2
1.052
1.030
1.062
1.100
0.860
0.882
1.078
R(Fo), [I > 2
s
(I)]
0.0234
0.0597
0.000(5)
0.257/ꢀ0.245
0.0188
0.0512
e
0.0179
0.0459
e
0.0248
0.0698
e
0.0268
0.0571
e
0.0309
0.0543
0.0444
0.1137
e
Rw(Fo2)
Flack parameter
[e Åꢀ3
ꢀ0.02(2)
Δ
r
]
0.775/ꢀ0.577
0.523/ꢀ0.732
0.317/ꢀ0.406
0.354/ꢀ0.268
0.378/ꢀ0.221
3.248/ꢀ1.935

A.C. Tagne Kuate et al. / Journal of Organometallic Chemistry 696 (2012) 4281e4292
4285
Table 2
Crystal and structure refinement data for 9, 9$THF, 10e12, 14, and 15.
9
9$THF
10
11
12
14
15
Empirical formula
C44H42OTi2Zr2
10.1506(2)
10.9013(2)
16.2339(4)
90
104.544(2)
90
1738.79(6)
2
C48H50O2Ti2Zr2
44.4138(18)
8.3540(2)
25.3490(10)
90
123.881(6)
90
7808.3(5)
8
C44H42OTi2Hf2
10.1408(2)
10.8733(2)
16.2218(2)
90
104.731(2)
90
1729.89(5)
2
C24H26HfOTi
15.7895(4)
7.6609(2)
17.1629(6)
90
104.559(2)
90
2009.39(10)
4
C12H11ITi
12.5493(2)
7.9906(2)
10.7922(2)
90
93.750(2)
90
1079.89(4)
4
C24H22Ti2
10.4597(8)
8.1360(6)
10.7751(13)
90
102.903(8)
90
893.81(13)
2
C18H16Ti
10.828(2)
7.8912(16)
15.797(5)
90
97.91(3)
90
1336.9(5)
4
a (Å)
b (Å)
c (Å)
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
V (Å3)
Z
Formula weight
Space group
T (K)
865.02
P21/c
100(2)
1.54184
1.652
8.821
937.12
C2/c
100(2)
1.54184
1.594
7.926
1039.56
P21/c
100(2)
1.54184
1.996
14.809
556.84
P21/n
100(2)
0.71073
1.841
5.571
330.01
P21/c
100(2)
0.71073
2.030
406.22
P21/n
100(2)
1.54184
1.509
280.21
P21
100(2)
0.71073
1.392
l
(Å)
Dcalcd (g cm-3
(mmꢀ1
Reflection collected
)
m
)
3.606
30,198
7.602
11,482
0.621
47,404
17,238
46,302
20,351
49,844
Independent reflections 3614 Rint ¼ 0.0287 8092 Rint ¼ 0.0403 3571 Rint ¼ 0.0267 5414 Rint ¼ 0.059 2370 Rint ¼ 0.0349 1842 Rint ¼ 0.0952 5462 Rint ¼ 0.1163
Goodness of fit on F2
1.045
1.070
1.060
0.878
1.006
1.023
0.834
R(Fo), [I > 2
s
(I)]
0.0259
0.0692
e
0.0262
0.0710
e
0.0180
0.0465
e
0.0206
0.0259
e
0.0144
0.0332
e
0.0527
0.1443
e
0.0523
0.1133
Rw(Fo2)
Flack parameter
[e Åꢀ3
ꢀ0.03(4)
Δ
r
]
0.796/ꢀ0.707
0.537/ꢀ0.565
0.714/ꢀ0.843
1.101/ꢀ1.083
0.336/ꢀ0.354
0.750/ꢀ0.558
1.584/ꢀ0.736
3. Results and discussion
a zircona[1]troticenophane by the reaction of the dilithiated troti-
cene [(
7-C7H6Li)Ti( 5-C5H4Li)]$pmdta (1a) [25] with 1 eq. of [(h5
C5Me5)2ZrCl2]. Similar reactions with the sterically less hindered
zirconocene and hafnocene dichlorides, [(
5-C5H5)2ZrCl2] and [(h5
C5H5)2HfCl2], also failed to furnish the desired Zr- or Hf-bridged
ansa-Cht-Cp complexes 90 and 100 (Scheme 3), and the
-oxo zir-
h
h
-
3.1. Synthesis and spectroscopic characterization of Cp-functionalized
mono- and bitroticenes
h
-
The monolithiated troticene derivative [(
h
7-C7H7)Ti(h5
-
m
C5H4Li)]$pmdta (1b) was synthesized according to the published
procedure [25]. Its treatment with stoichiometric amounts of
dichlorodiphenylsilane (Ph2SiCl2) or dichlorodi-tert-butylstannane
(tBu2SnCl2) in hexane at ꢀ78 ꢁC afforded the troticenyl chlorosilane
2 and the troticenyl chlorostannane 3 as blue and blue-green
crystalline solids in 78% and 42% yield, respectively. Similarly, 1b
conocene- and hafnocene-bridged bitroticenes 9 and 10 were the
only compounds that could be isolated from hexane solutions. In
view of similar reactivities reported for zircona- and hafna[1]fer-
rocenophanes upon exposure to moist air [32], we assume that the
formation of 9 and 10 can also be ascribed to the reaction of 90 and
100 with residual water from the solvent or the glassware. Unfor-
tunately, all attempts to isolate these strained complexes under
strictly inert conditions proved unsuccessful and always afforded
reacted with half an equivalent of PhPCl2, (Me3Si)2NBCl2 and [(h5
-
C5H5)2TiCl2] to yield the phosphane-, borane- and titanocene-
bridged bitroticenes 5e7 in almost quantitative yields (Scheme
1). Compound 3 partially hydrolyzed in the presence of moisture,
and presumably, the condensation of an intermediate organotin
hydroxide resulted in the formation of the bis(troticenyl) organo-
stannoxane 4 as a green solid (Scheme 2).
the
recent report by Braunschweig et al. on the isolation of a [1]tro-
chrocenophane containing a bridging [(
5-C5H4tBu)2Zr] moiety
m-oxo species 9 and 10. This observation is in contrast to the
h
[24]. Our failure to isolate 90 and 100 might be ascribed to insuffi-
cient steric protection of the ipso-C7H6emetal bonds by the C5H5
ligands and also to higher strain, since the titaniumecarbon bonds
in troticenes are longer than the chromium-carbon bonds in
The bimetallic troticenylezirconium complex 8 was obtained as
a by-product in very low yield during our attempts to synthesize
Scheme 1. Synthesis of Cp-substituted troticenes; reagents: (i) Ph2SiCl2; (ii) 0.5 eq.
Cl2BN(SiMe3)2; (iii) 0.5 eq. [Cp2TiCl2]; (iv) 0.5 eq. PhPCl2; (v) tBu2SnCl2.
Scheme 2. Hydrolysis of compound 3 and formation of the organostannoxane 4.

4286
A.C. Tagne Kuate et al. / Journal of Organometallic Chemistry 696 (2012) 4281e4292
Scheme 3. Attempted synthesis of Zr- and Hf-bridged [1]troticenophanes.
trochrocenes [18,19]. Further evidence for the high reactivity of 100
stems from an attempted recrystallization of the reaction mixture
from diethyl ether, which afforded crystals of the ethoxide complex
11; this might have formed by ether cleavage and elimination of
ethylene promoted by 100 (Scheme 3).
The reactions of 1b with 1,2-diiodoethane and zinc dichloride
(ZnCl2) furnished the iodo- and zinc-substituted troticenes 12 and
13 as green solids in good yield. Negishi carbonecarbon cross-
coupling between both compounds catalyzed by [Pd(dppf)Cl2]
afforded the interannularly bridged [5e5]bitroticene 14 as a green
crystalline solid in 26% yield. Similarly, the phenyl-substituted
troticene 15 was obtained in 46% yield through a coupling reac-
tion between 13 and iodobenzene (Scheme 4).
Compounds 2e7, 12, 14 and 15 are readily soluble in nonpolar
solvents such as hexane and/or toluene, while compounds 8e11 are
sparingly soluble in hexane but readily dissolve in tetrahydrofuran
and dichloromethane. All compounds are sensitive toward air and
moisture but can be stored in a glove box in an argon atmosphere
for several months. Except for compounds 4 and 11, which could
not be isolated in sufficient quantities for NMR spectroscopic
characterization, the 1H NMR spectra of all complexes showed
a splitting pattern characteristic for substituted Cp rings, whereby
two pseudotriplet resonances assigned to the
a- and b-C5H4
protons are observed in the range from 4.62 (12) to 5.58 ppm (8);
the C7H7 protons give rise to a singlet resonance between 5.34 (14,
15) and 5.83 ppm (9). In addition, the 1H NMR spectrum of the
Scheme 4. Negishi cross-coupling reactions involving the zincated troticene 13.

A.C. Tagne Kuate et al. / Journal of Organometallic Chemistry 696 (2012) 4281e4292
4287
troticenyl chlorostannane 3 exhibits long-range 3J(1He117/119Sn)
and 4J(1He117/119Sn) coupling constants of 12.8/17.9 and 12.3/
17.3 Hz, respectively, between the tin atom and the Cp hydrogen
atoms. The resonance for the tert-butyl protons appears at 1.24 ppm
and shows 2J(1He117/119Sn) coupling constants of 82.9/86.7 Hz.
The 13C NMR spectra of compounds 2, 3, 6, 7, 9, 10 and 12 display
three resonances for the Cp ring ranging from 100.0 (3) to
147.3 ppm (9). The magnetically equivalent Cht carbon atoms in the
13C NMR spectra of 2, 3, 6, 7, 9, 10 and 12 are observed as singlet
resonances between 85.5 (9) and 89.1 ppm (12). These values are
close to that reported for the C7H7 carbon NMR signal in troticene
(86.4 ppm) [26]. The 13C NMR resonance for the quaternary tBu
carbon atoms in
3
is found at 36.0 ppm with 1J(13Ce117/
119Sn) ¼ 423.7/402.3 Hz, which falls in the expected range for
a four-coordinate tin atom [33]. The 119Sn NMR spectrum of 3
showed a single resonance at 30.3 ppm, which is significantly
shifted to higher field in comparison with the value reported for the
Fig. 3. ORTEP diagram of 2 with thermal displacement parameters drawn at the 50%
5-C5H5)Fe(
h
5-C5H4SnCltBu2)](
d
¼ 72.3 ppm)
probability level. Selected bond lengths [Å] and angles [ꢁ]: SieCl
¼
2.0694(6),
ferrocene analogue [(
h
[34]. As a result of coupling with the phosphorus atom, the Cp
carbon atoms in the 13C NMR spectrum of 5 appear as doublet
resonances at 103.2 (ipso-C), 101.8 and 100.2 ppm with 1J(13Ce31P),
2J(13Ce31P) and 3J(13Ce31P) coupling constants of 17.0, 9.8 and
2.8 Hz, respectively. The 31P NMR spectrum of 5 shows a single
resonance at ꢀ29.2 ppm, shifted to higher field in comparison with
SieC(13)
¼
1.8603(17), SieC(19)
¼
1.8599(17), C(8)eSieCl
¼
106.5(6), C(8)e
SieC(19) ¼ 113.9(8), C(8)eSieC(13) ¼ 110.8(8), C(19)eSieC(13) ¼ 109.1(7), C(19)e
SieCl ¼ 108.3(6), C(13)eSieCl ¼ 108.2(5).
atoms ranging from 106.5(8)ꢁ to 113.9(8)ꢁ and from 100.5(5)ꢁ to
118.1(7)ꢁ. The SieC(8) distance of 1.8540(17) Å in 2 is similar to the
SieC(phenyl) bond lengths of 1.8599(17) and 1.8603(17) Å, while
the SneC(8) distance of 2.1218(16) Å in 3 is slightly shorter than the
two SneC(tBu) bonds of 2.1743(17) and 2.1828(17) Å. The SieCl and
SneCl bonds of 2.0694(6) and 2.3915(4) Å are close to those re-
ported for related ferrocenyl chlorosilanes and chlorostannanes;
[(h
7-C7H7)Ti(
h
5-C5H4PPh2)] (
d
¼ ꢀ17.5 ppm) [25,28]. The 11B NMR
spectrum of 6 displays a broad resonance at 36.7 ppm. The UV/vis
spectrum of [5e5]bitroticene (14) was recorded in toluene,
showing a weak band at 689 nm (
3
¼ 30 L molꢀ1 cmꢀ1), which is
similar to the values reported for troticene [11a,16,35]. For 14 and
15, the molecular ions [(h h h
7-C7H7)Ti( 5-C5H4Ph)]þ and [( 7-C7H7)
5-C5H4)]þ2 were detected at m/z ¼ 280 and 406 by electron
e.g. 2.0802(10) Å in [(
[(
5-C5H4SiClPh2)Fe(
C5H5)Fe(
5-C5H3SnClMe2)(BClPh)] [38].
h
h
5-C5H5)Fe(
h
5-C5H4)]3SiCl [37a], 2.080(1) Å in
Ti(
h
h
5-C5H4)]2BCl [37b], and 2.4026(26) Å in [(h5
-
ionization mass spectrometry (EI-MS).
h
The C(8)eI distance of 2.0797(17) Å in 12 and the C(8)eC(13)
distance of 1.467(8) Å in 15 are in agreement with the corre-
3.2. Molecular structures of the Cp-functionalized monotroticenes
2, 3, 8, 11, 12 and 15
sponding bond lengths reported for the ferrocenyl iodide [(h5
-
C5H5)Fe(
trovacene [(
h
5-C5H3I)(CHO)] [2.083(7) Å] [39] and for the phenyl-
5-C7H7)V( 5-C5H4Ph)] [1.478(15) Å] [40]. The inter-
Suitable crystals for X-ray structure determinations were ob-
tained by cooling saturated solutions of the compounds in pentane
(3), toluene (2, 12, 15) and Et2O (11) at ꢀ30 ꢁC or by slow evapo-
ration of a THF/hexane solution of 8 at room temperature. The
molecule of compound 12 displays approximate mirror symmetry
(r.m.s. deviation 0.24 Å). Compound 15 crystallizes with two
independent but similar molecules differing only in the orientation
of the phenyl ring (a least-squares fit gave an r.m.s. deviation of
0.09 Å); only one is discussed here. The molecular structures of all
these compounds are shown in Figs. 3e8, and selected bond
lengths and angles are summarized in Table 3.
h
h
planar angle between the C5H4 ring and the phenyl substituent in
15 is 17.9(2)ꢁ. The zirconium and hafnium atoms in compounds 8
and 11 adopt a characteristic, strongly distorted pseudo-tetrahedral
configuration with the CpcteZreChtct and CpcteHfeChtct angles of
134.6ꢁ (8) and 129.5ꢁ (11) and the C(8)eZreCl and C(8)eHfeO
angles of 91.5(9)ꢁ (8) and 98.7(8)ꢁ (11), respectively. Thereby, the
The bond distances between the titanium atom and the carbon
atoms of the five-membered rings fall in the ranges 2.3273(17)e
2.3411(17) (2), 2.3226(16)e2.3345(17) (3), 2.284(4)e2.395(3) (8),
2.305(2)e2.339(2) (11), 2.3236(17)e2.3469(17) (12) and 2.315(5)e
2.349(5) (15) Å. As expected, and in agreement with the molecular
structure of the unsubstituted troticene [36], the TieC5H4 carbon
bonds are significantly longer than the corresponding TieC7H7
distances [2.2020(19)e2.2122(18) (2), 2.1996(17)e2.2221(18) (3),
2.209(4)e2.253(5) (8), 2.201(3)e2.223(3) (11), 2.1944(17)e
2.2106(17) (12), 2.198(6)e2.212(5) (15) Å], reflecting the stronger
metaleligand interactions with the Cht ring [19]. The two rings are
nearly parallel, as evidenced by the CpcteTieChtct (ct ¼ ring
centroid) angles of 177.9ꢁ (2), 174.3ꢁ (3), 170.1ꢁ (8), 174.2ꢁ (11),
177.2ꢁ (12) and 178.0ꢁ (15) (Table 1). These values deviate only
slightly from the ideal linear arrangement, with the maximum
deviation being observed for the zirconocene-bridged troticene 8.
The silicon and tin atoms in compounds 2 and 3 adopt distorted
tetrahedral configurations with the angles about the Si and Sn
Fig. 4. ORTEP diagram of 3 with thermal displacement parameters drawn at the 50%
probability level. Selected bond lengths [Å] and angles [ꢁ]: SneCl
¼
2.3915(4),
100.5(5), C(8)e
SneC(13)
¼
2.1743(17), SneC(17)
¼
2.1828(17), C(8)eSneCl
¼
SneC(17) ¼ 117.1(6), C(8)eSneC(13) ¼ 113.4(7), C(17)eSneC(13) ¼ 118.1(7), C(17)e
SneCl ¼ 101.2(5), C(13)eSneCl ¼ 102.4(5).

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A.C. Tagne Kuate et al. / Journal of Organometallic Chemistry 696 (2012) 4281e4292
Fig. 5. ORTEP diagram of 8 with thermal displacement parameters drawn at the 50%
probability level. Selected bond lengths [Å] and angles [ꢁ]: ZreCl
2.4425(9),
¼
ZreCcp ¼ 2.523(3)e2.604(3), C(8)eZreCl ¼ 91.5(9), C(8)eZreCpct ¼ 103.0 and 111.5,
Fig. 7. ORTEP diagram of 12 with thermal displacement parameters drawn at the 50%
probability level.
CpcteZreCl ¼ 103.1 and 104.7, CpcteZreCpct ¼ 134.6.
angles at Zr in 8 are very similar to those in the closely related
ferrocenyl-zirconium derivative [(h h -
5-C5H5)Fe{ 5-C5H4ZrCl(h5
(Table 4). Compound 4 represents, to the best of our knowledge, the
first example of a structurally characterized metallocene-supported
organostannoxane in which the tin atoms are directly bound to the
CnHnꢀ1 ring. In contrast, organostannoxanes containing ferrocene
units have been obtained from the reaction between ferrocenyl
carboxylic acid and an organotin oxide or hydroxide, leading to
C(O)O-bridged molecules [42,43]. Both tin atoms in 4 reside in
a distorted tetrahedral environment with the angles ranging
between 101.7(6)ꢁ and 114.9(7)ꢁ (at Sn1) and between 107.5(6)ꢁ
and 120.0(7) (at Sn2). The Sn(1)eC(8) and Sn(2)eC(20) distances
are 2.1374(17) and 2.1491(16) Å, which is markedly longer than the
corresponding distance in 3 [2.1218(16) Å] and the Sn(1)eC(15)
C5Me5)2}] [135.4(1)ꢁ and 91.9(1)ꢁ], which also exhibits almost
identical [ZreCl ¼ 2.456(2) Å, ZreC ¼ 2.314(7) Å] distances to those
in 8 (Table 3) [41].
3.3. Molecular structures of the Cp-functionalized bitroticenes 4e7,
9, 9$THF, 10 and 14
Single crystals for X-ray diffraction analysis were obtained by
cooling saturated solutions of the compounds in toluene (5, 7, 9, 10)
or diethyl ether (14) or by slow evaporation of a solution of the
respective compound in THF (9$THF), hexane (4) and THF/dieth-
ylether (1:2) (6) at room temperature. Compound 9 crystallized
without solvent from toluene solution, but as 9$THF from tetra-
hydrofuran solution. The molecular structures of complexes 4e7,
9$THF, 10 and 14 are presented in Figs. 9e15. Selected bond
distances and angles are assembled in Table 4. The molecular
structures of 9 and 10 are isotypic, and therefore, only the structure
of 10 is shown (Fig. 14).
In a similar fashion to that discussed for the monotroticenes
(vide supra), all ChteCp sandwich moieties are affected by the
variable substitution pattern, and the maximum deviation from an
ideal CpcteTieChtct angle of 180ꢁ is observed for 7 (170.5ꢁ for both
troticenyl fragments). Similar TieC bond lengths are also observed,
with the metal-carbon distances to the seven-membered ring being
significantly shorter than those to the five-membered ring
bond length in the dimeric diferrocenyltin dihydroxide [(
h
5-C5H5)
Fe{h
5-C5H3(CH2NMe2)2Sn(OH)2]2 [2.12(2) Å] [44]. The bent nature
of the stannoxane core is reflected by the Sn(1)eOeSn(2) angle of
145.2(7)ꢁ, which is somewhat larger than the corresponding angle
found in hexaphenyldistannoxane, (Ph3Sn)2O [137.8(3)ꢁ] [45], and
deviates considerably from a linear arrangement as reported for the
distannoxanes (tBu3Sn)2O [46] and [(PhCH2)3Sn]2O [47].
The overall structure of the phosphorus-bridged bitroticene 5 is
very similar to the corresponding biferrocenylphenylphosphane
[(h h
5-C5H5)Fe( 5-C5H4)]2PPh [48] with the sandwich moieties
adopting an almost perpendicular orientation, as indicated by an
angle of 81.2(6)ꢁ between the two Cp planes. The boron-bridged
complex 6 displays crystallographic C2 symmetry, and substitu-
tion of the trigonal-pyramidal phosphorus atom in 5 by a trigonal-
planar boron atom in 6 affords an anti-orientation of the troticene
moieties with Cp ligands that deviate by 26.1(6)ꢁ from a perfectly
coplanar orientation. The angle between the NSi2 and BC2 planes is
72.4(3)ꢁ, indicating that an effective BeN
p-interaction is not
possible, and consequently, the BeN bond length [1.468(3) Å] in 6 is
considerably longer than observed for the planar species
Fig. 6. ORTEP diagram of 11 with thermal displacement parameters drawn at the 50%
probability level. The carbon atoms of the ethanolate fragment are disordered over two
positions. Selected bond lengths [Å] and angles [ꢁ]: HfeO
¼
1.9075(17),
101.7/106.7,
HfeCcp
¼
2.502(3)e2.541(3), C(8)eHfeO
¼
98.6(8), C(8)eHfeCpct
¼
Fig. 8. ORTEP diagram of 15 with thermal displacement parameters drawn at the 50%
probability level.
CpcteHfeO ¼ 107.9 and 108.0, CpcteHfeCpct ¼ 129.5.

A.C. Tagne Kuate et al. / Journal of Organometallic Chemistry 696 (2012) 4281e4292
4289
Table 3
Selected bond lengths (Å) and angles in 2, 3, 8, 11, 12 and 15.
2
3
8
11
12
15
E ¼ Si
E ¼ Sn
E ¼ Zr
E ¼ Hf
E ¼ I
E ¼ C(13)
TieCCht
TieCCp
TieCt7
2.2020(19)e2.2122(18)
2.3273(17)e2.3411(17)
1.486
2.1996(17)e2.2221(18)
2.3226(16)e2.3345(17)
1.492
2.209(4)e2.253(5)
2.284(4)e2.395(3)
1.539
2.201(3)e2.223(3)
2.305(2)e2.339(2)
1.496
2.1944(17)e2.1940(17)
2.3236(17)e2.3469(17)
1.481
2.201(5)e2.214(5)
2.313(5)e2.349(5)
1.475
TieCt5
1.998
1.994
1.966
1.980
2.002
1.992
EeC(8)
1.8540(17)
2.1218(16)
2.323(3)
2.275(2)
2.0797(17)
1.465(8)
CpcteTi(1)eChtct
177.9
174.3
170.1
174.2
177.2
178.0
Fig. 11. ORTEP diagram of 6 with thermal displacement parameters drawn at the 50%
Fig. 9. ORTEP diagram of 4 with thermal displacement parameters drawn at the 50%
probability level. Selected bond lengths [Å] and angles [ꢁ]: Sn(1)eO ¼ 1.9569(12),
Sn(2)eO ¼ 1.9575(12), Sn(1)eC(25) ¼ 2.1832(17), Sn(1)eC(29) ¼ 2.1784(18), Sn(2)e
C(33) ¼ 2.1881(17), Sn(2)eC(37) ¼ 2.1864(18), C(8)eSn(1)eO ¼ 104.5(6), C(8)eSn(1)e
C(25) ¼ 114.9(7), C(8)eSn(1)eC(29) ¼ 113.8(7), C(25)eSn(1)eC(29) ¼ 115.7(7), C(25)e
Sn(1)eO ¼ 104.2(6), C(29)eSn(1)eO ¼ 101.7(6), C(20)eSn(2)eO ¼ 107.5(6), C(20)e
Sn(2)eC(33) ¼ 115.1(7), C(20)eSn(2)eC(37) ¼ 109.3(7), C(33)eSn(2)eC(37) ¼ 102.0(7),
C(33)eSn(2)eO ¼ 97.9(6), C(37)eSn(2)eO ¼ 105.3(6), Sn(1)eOeSn(2) ¼ 145.2(7).
probability level. Selected bond lengths [Å] and angles [ꢁ]: BeN
NeSi 1.7456(8), C(8)eBeC(8A) 122.3(17), C(8)eBeN
BeNeSi ¼ 119.20(4).
¼
1.468(3),
118.83(8),
¼
¼
¼
ZreOeZr(A) and HfeOeHf(A) angles and short ZreO and HfeO
bond lengths of 1.94560(14) and 1.9364(1) Å, whereas the formally
C1-symmetric molecule in 9$THF (the approximate symmetry is
twofold, r.m.s. deviation 0.11 Å) displays a bent Zr(1)eOeZr(2)
arrangement [165.5(8)ꢁ] with ZreO bond lengths of 1.9427(13) and
1.9651(13) Å. Similar structural parameters were reported for the
(C6F5)2BN(CH2)4 [1.366(3)ꢁ] [49]. The titanocene-bridged complex
7 also displays crystallographic C2 symmetry but is close to C2v
(r.m.s. deviation 0.11 Å), with a pseudo-tetrahedral geometry at the
Ti(2) atom. Interestingly, 7 can be regarded as a dimetalated
derivative of tetrakis(cyclopentadienyl) titanium, which was shown
to exhibit fast hapticity interconversion in solution and to display
oxo-bridged dinuclear complexes [(Cp2ZrMe)2(m-O)] [54] and
[(Cp2HfMe)2( -O)] [55]. Finally, the pentafulvalene complex 14
m
adopts an exact trans-conformation with the cyclopentadienyl
rings being perfectly coplanar, as a consequence of crystallographic
inversion symmetry (and approximate C2h symmetry, r.m.s. devi-
ation 0.07 Å). Such an ideally parallel orientation of the troticenyl
units in 14 has been previously observed in the crystal structures of
a [(
Similar structural features to those found in 7 (Table 2) were also
h h
5-C5H5)2Ti( 1-C5H5)2] structure in the solid state [50,51].
reported for Cp2Ti-bridged biferrocenes such as [(
h
5-C5H5)Fe(h5
h
5-C5H4eCH2N(CH3)2}Fe(h5
-
-
C5H4)]2[Ti(
h
5-C5H5)2] [52] and [{
5-C5H5)2] [53].
biferrocene, [(
[(
7-C7H7)V( 5-C5H4)]2, [40]. This is in contrast to the crystal
structure of [7e7]bitrovacene [(
5-C5H5)V( 7-C7H6)]2, in which the
h h
5-C5H5)Fe( 5-C5H4)]2 [56], and [5e5]bitrovacene,
C5H4)]2[Ti(
h
h
h
The isotypic complexes 9 (solvent-free form) and 10 crystallize
with imposed inversion symmetry (and approximate C2h
symmetry, r.m.s. deviation 0.12 Å), furnishing exactly linear
h
h
trovacenyl fragments are almost perpendicular to one another [57].
In 14, the Cp and Cht rings in each troticenyl moiety are nearly
coplanar as evidenced by the dihedral angle between both planes
[1.42(1)ꢁ], which is smaller than the corresponding angle of 2.2(3)ꢁ
Fig. 10. ORTEP diagram of 5 with thermal displacement parameters drawn at the 50%
probability level. Selected bond lengths [Å] and angles [ꢁ]: PeC(20) ¼ 1.8232(14),
PeC(25) ¼ 1.8381(13), C(8)ePeC(20) ¼ 98.3(6), C(8)ePeC(25) ¼ 100.0(6), C(25)e
PeC(20) ¼ 102.3(6).
Fig. 12. ORTEP diagram of 7 with thermal displacement parameters drawn at the 50%
probability level. Selected bond lengths [Å] and angles [ꢁ]: Ti(2)eCcp ¼ 2.394(2)e
2.419(2), C(8)eTi(2)eC(8A) ¼ 92.0(11), C(8)eTi(1)eCpct ¼ 106.0 and 107.7, CpcteTi(2)e
Cpct ¼ 130.8.

4290
A.C. Tagne Kuate et al. / Journal of Organometallic Chemistry 696 (2012) 4281e4292
Fig. 13. ORTEP diagram of 9$THF with thermal displacement parameters drawn at
the 50% probability level. Selected bond lengths [Å] and angles [ꢁ]: Zr(1)e
O
¼
1.9427(13), Zr(2)eO
Ccp ¼ 2.2927(18)e2.5701(19), C(8)eZr(1)eO ¼ 96.2(6), C(8)eZr(1)eCpct ¼ 105.6/
105.8, OeZr(1)eCpct 106.7/108.4, C(20)eZr(2)eO 95.7(6), C(20)eZr(2)e
Cpct 105.8/106.2, OeZr(2)eCpct 106.4 and 107.8, CpcteZr(1)eCpct 129.3,
CpcteZr(2)eCpct ¼ 128.8, Zr(1)eOeZr(2) ¼ 165.5(8).
¼
1.9651(13), Zr(1)eCcp
¼
2.518(2)e2.569(2), Zr(2)e
¼
¼
¼
¼
¼
Fig. 14. ORTEP diagram of 10 with thermal displacement parameters drawn at the
50% probability level. Selected bond lengths [Å] and angles [ꢁ]: HfeO ¼ 1.9364(1),
HfeCcp ¼ 2.509(2)e2.543(2), C(8)eHfeO ¼ 90.8(6), C(8)eHfeCpct ¼ 106.6 and 108.6,
OeHfeCpct
Compound 9 is isotypic to 10.
¼
107.9 and 109.2, CpcteHfeCpct
¼
127.5, HfeOeHf(A)
¼
180.0.
found in the non-bridged troticene [(h h
7-C7H7)Ti( 5-C5H5)] [58].
The CeC bond lengths (Table 4) within the cyclopentadienyl
ligand [1.417(6)1e1.419(5) (mean 1.417) Å] in 14 are slightly
lengthened as compared with those reported for troticene
[1.386(5)e1.404(8) (mean 1.396) Å] [58], but they are in agree-
ment with those measured in biferrocene [CeC ¼ 1.35e1.45
(mean 1.40) Å] [56] and [5e5]bitrovacene [CeC ¼ 1.406(2) Å
(mean) ] [40]. In these structures, the lengths of the CeC bond
linking two Cp rings [1.48(4) Å and 1.468(5) Å, respectively] are
close to the 1.464(7) Å found in 14.
Fig. 15. ORTEP diagram of 14 with thermal displacement parameters drawn at the
50% probability level.

A.C. Tagne Kuate et al. / Journal of Organometallic Chemistry 696 (2012) 4281e4292
4291
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A series of Cp-substituted troticene and bitroticene complexes
have been synthesized and characterized starting from mono- or
dilithiated troticene. These compounds represent important
examples for the direct attachment of different substituents to the
Cp ring including halide, chloroorganosilane, chloroorgan-
stannane or metallocene monochloride. The presence of func-
tional bonds such as C5H4eI, C5H4eSieCl, C5H4eSneCl or
C5H4eZreCl in these complexes allows their use as synthons for
further reactions. Indeed, the troticenyl chloroorganostannane 3 is
partially converted to the organostannoxane 4 when exposed to
moisture. Compound 4 represents the first structurally charac-
terized metallocene-supported organostannoxane with a direct
C5H4eSn bond. Using the troticenyl iodide 12 and iodobenzene,
we also achieved successful palladium-catalyzed Negishi CeC
cross-coupling reactions and isolated the fulvalene complexes 14
and 15. Further important findings described in this work are the
heterobimetallic oxo complexes 9 and 10 isolated during our
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and 100. These latter might exist in solution, but appear to
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ipso-CeM bond cleavage in contact with any trace of moisture
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Acknowledgments
This work was partially supported by the Deutsche For-
schungsgemeinschaft through the focus program SPP 1118
‘‘Secondary Interactions as a Steering Principle for the Selective
Functionalization of Non-Reactive Substrates” [59]. A.C.T.K is
grateful to the Alexander von Humboldt Foundation for a post-
doctoral fellowship.
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Appendix A. Supplementary material
CCDC 839987e840000 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via www.
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